To improve the resolution of printers, there are ongoing efforts to reduce the size of the individual nozzle structures. Smaller nozzles eject smaller ink drops that are closer together because of the reduced nozzle spacing on the printhead. Print resolution commonly measured as dots per inch (dpi), can also be improved by moving the nozzle array over the part of the media substrate several times. However, this comes at a heavy cost to print speed.
There are a great many difficulties associated with the fabrication of nozzles at a micron scale. One of major design concerns is the operational life of the individual nozzle. The microscopic structures in the nozzles are not robust and can fail from burning out (oxidation of metallic components), trapped air bubbles and so on. They are also more susceptible to problems such as clogging from paper dust, ink kogation and other contaminants.
In light of this, the design of inkjet printheads strives to maximize the operational life of the individual nozzles while reducing the nozzle size for greater print resolutions.